Step 1: Identify the organism in question.
The organism is Antedon, also commonly known as Feather Star. Step 2: Recall the characteristics of the major animal phyla.
Protochordata: These are primitive chordates, typically marine, filter feeders, and include organisms like tunicates and lancelets. They possess a notochord at some stage of development.
Echinodermata: This phylum consists of marine invertebrates characterized by radial symmetry (usually pentaradial in adults), a spiny skin, and a water vascular system. Examples include starfish, sea urchins, brittle stars, sea cucumbers, and crinoids (like feather stars).
Mollusca: This phylum includes soft-bodied invertebrates, many of which have a hard shell. Examples include snails, clams, octopuses, and squids.
Arthropoda: This is the largest phylum in the animal kingdom, characterized by segmented bodies, jointed appendages, and an exoskeleton. Examples include insects, spiders, crustaceans, and myriapods. Step 3: Classify Antedon based on its characteristics.
Antedon, or the Feather Star, belongs to the class Crinoidea within the phylum Echinodermata. They exhibit radial symmetry and possess features characteristic of echinoderms. Step 4: Compare with the given options.
(1) Protochordata: Incorrect.
(2) Echinodermata: Correct, as Feather Stars are a type of echinoderm. (3) Mollusca: Incorrect.
(4) Arthropoda: Incorrect.
(2) Echinodermata